Track shunting apparatus



Dec. 3, 1935.

.C. R. BEALL.

TRACK SHUNTING APPARATUS Original Filed lies. 22, 1952 INVENTOR Giza/lay A Baal! BY QQVLTIMJZ HIS ATTORNEY Patented Dec. 3, 1935 UNITED STATES PATENT OFFICE TRACK SHUNTING APPARATUS A plic t ecember 22, 3 2 S ria N 643 3 5 Renewed October 28 1933 6 Claims.

My invention relates to track shunting apparatus and more specifically to apparatus for shunting track circuits by light weight rail vehicles having steel wheels or pneumatic tired wheels.

I will describe one form of track shunting apparatus embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

In providing effective shunting protection to a rail car, it is usually desirable to install shunting apparatus at both ends of the car, so that traffic will not be endangered should the car be located in such manner as to foul an adjacent track. Another advantage of this arrangement is that increased protection against loss of shunt is obtained because even though one track shunting path may be momentarily interrupted for any reason such as vibration of the rail shoes in passing over rail joints, or because of heavy scale at portions of the rail surface, another shunting path will usually remain effective. However, when the rail shoes associated with a pair of such paths are located on opposite sides of a pair of insulated rail joints, there exists the danger of feedover of track circuit current around the rail joints through the shunting circuit, which may result in false or undesirable operation of, a track relay in an adjoining track circuit.

One object of my invention is to decrease the possibility of such false operation, and at the same time, to provide a reliable shunting arrange ment in which a relatively high rail film breakdown voltage is maintained across a pair of shoes making imperfect contact with the rails, irrespective of the fact that the other pair of rail shoes is or is not providing a low impedance path from rail to rail.

Referring to the drawing, I have shown a stretch of railway track A-C divided by insulated joints 2 into the track sections AB and B?C, each of which is provided with a track relay and a track transformer, in the usual manner. Reactors X and X connected in series with track transformers T and T respectively, are the usual track current limiting reactors, and the track relays R and R are of the two-element type having a track winding 3 and a local winding 4, in order that broken-down insulated rail joint protection may be obtained by staggering the relative polarities of adjoining track circuits. The remaining apparatus which is illustrated is intended to be carried on the rail car.

The generator G, which is driven by a motor M energized from the car battery CB, supplies current to primary windings 5 and ll] of transformers T and T respectively, through current limiting reactors X and X and through a re- 5 actor K the purpose of which will be explained hereinafter. The secondary voltage induced in winding 6 of transformer T is applied across the two rails of the track by means of rail shoes 1 and 8, to break down the resistance: film which 0 may exist between the shoes and the rail. A return path for the film breakdown current is pro. vided by the rail to rail connection 9, which, as illustrated, comprises a pair of rail shoes I6 and I! connected together electrically, but which in 15 the case of a steel wheeled car may be replaced by an axle of the car and its associated wheel pair.

Secondary winding ll of transformer T supplies film breakdown voltage to rail shoes I2 and 20 I3, and rail connection l4 serves as the return path for the current of winding ll. Connections 9 and I4 are useful not only in providing low impedance return paths for the film breakdown current, but also in providing a more effec- 5 tive track shunt because of the lower impedance of these connections as compared with the impedance of windings 6 and II. Wire 20, connecting rail shunts 9 and 14, makes it possible for a shoe of group l6,I'| or lS-IS to make imperfect rail contact without materially affecting the shuntin protection. By placing shoes 12 and I3 at the forward end, and shoes 1 and 8 at the rear end of the car, protection to both ends of the car at foulings, crossovers, etc., is secured.

Although the frequency of the current supplied by generator G will, in practice, be considerably higher than the frequency of the track circuit source BX7-CX, so that false operation of the track relays by'current from generator G may 40 not result, however, when the car spans insulated joints, there exists the possibility of feedover of track circuit current, from track transformer T for example, through transformers T and T to the track relay R This possibility is particularly dangerous if the rail shoes l5'|1 and |8-|9 are making imperfect rail contact. To minimize this danger, a high impedance reactor X is provided, this reactor being connected between windings 5 and H) of transformers T and T in the path of any track circuit current which may tend to be fed from section AB to section B-C, over the track shunting apparatus.

As will be apparent from the drawing, the currents which are supplied to transformers T and T from generator G, fiow in opposite directions in the two portions of reactor X and if these currents are substantially equal and wire I is connected at the midpoint of the reactor, the fluxes in the reactor core resulting from these currents will be substantially neutralized, so that no appreciable impedance, apart from the resistance of the reactor winding, will be introduced into the supply circuits of transformers T and T The reactors X and X are used to limit the maximum current which will be supplied by generator G in the case of perfect contact being made with the rails by the rail shoes, to conserve the energy of generator G and to decrease the drain on the car battery.

Apart from preventing feedover of track circuit current, reactor X is also useful in causing a relatively higher voltage to be maintained across rail shoes at one end of the car which are not making satisfactory rail contact, at such times as the rail contact of the shoes at the other end of the car is satisfactory. Under this condition, there will be unequal division of current in the two halves of reactor X and an increase in voltf age due to auto-transformer action in the reactor will occur, to aid the breakdown of the film in the higher resistance rail path.

If desired, reactors X and X may be replaced by a single reactor connected between generator G and the midpoint of reactor X replacing wire l5. It will be apparent that the apparatus illustrated is not limited in its application to the shunting of alternating current track circuits, but may also be used to shunt direct current track circuits.

The invention claimed in the present application is an improvement on the apparatus disclosed and claimed in an application for Letters Patent of the United States filed by Howard A. Thompson on August 16, 1932, Serial No. 629,030, for Apparatus for decreasing rail contact resistance.

Although I have herein shown and described only one form of track shunting apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a rail vehicle and a section of railway track, a source of varying current on said vehicle; two transformers on the vehicle, each having a primary winding energized from, said source and each having a secondary winding the potential of which is applied across the two rails of the track by means of a pair of rail shoes, one pair for each secondary winding, for breaking down the rail film between said rail shoes and the rail surface to improve shunting of said track; and a reactor connected between the primary windings of said two transformers for impeding the transfer of current between said two transformers and having an intermediate tap through which currents from said source are conducted to said primary windings in opposing directions in the two sections of said reactor thereby tending to decrease the reactor impedance in the energizing paths for the primary windings of said two transformers.

2. In combination with a rail vehicle and a section of railway track, a source of varying current on said vehicle, two transformers on the vehicle, each having a primary winding energized from said source and each having a secondary winding the potential of which is applied across the two rails of the track by means of a pair of rail shoes, one pair for each secondary winding for breaking down the rail film between said rail shoes and the 5 rail surface to improve shunting of said track; a reactor connected between the primary windings of said two transformers for impeding the transfer of current between said two transformers and having an intermediate tap through which curl0 rents from said source are conducted to said primary windings in opposing directions in the two sections'of said reactor thereby tending to decrease the reactor impedance in the energizing paths for the primary windings of said two transformers, and a low impedance connection from one to the other rail, carried by the vehicle, for providing a return path for the rail film breakdown current and for shunting said track.

3. In combination, a rail vehicle, a stretch of railway track divided into block sections each of which is supplied with alternating track circuit current at one end and an alternating current track relay at the other end of the section, a

source of varying current on said vehicle of such character as to be incapable of operating the track relays; two transformers on the vehicle, each having a primary winding energized from said source and each having a secondary winding the potential of which is applied across the two rails of the track by means of a pair of rail shoes, one pair for each secondary winding, for breaking down the rail film between said rail shoes and the rail surface to improve shunting of said track;

and a reactor connected between said two primary windings and having a mid-tap through which are conducted currents from said source for energizing said two primary windings, said currents flowing in opposite directions in the two halves of said reactor thereby tending to decrease the impedance of the supply circuits for said two primary windings, said reactor serving to impede the transfer of track circuit current from the track transformer of one block section to the track relay of an adjoining block section when said rail shoe pairs are located on opposite sides of insulated rail joints separating said block sections.

4. In a track shunting system for alternating current track circuits in which rail film breakdown potential is applied across the two rails of the track by means of rail shoes at a pair of separated locations along the track, the method of impeding the transfer of track circuit energy from one to an adjoining track circuit over the rail film breakdown circuit without substantially increasing the impedance of said rail film breakdown circuit, in which a series reactor is inserted in the track circuit energy transfer path, said reactor having an intermediate tap through which are conducted the rail film breakdown currents to the respective rail shoe pairs, said currents flowing in opposite directions in the two sections of said reactor thereby tending to decrease the impedance of said reactor to said rail film breakdown currents.

5. In combination with a rail vehicle and a section of railway track, a source of varying current on said vehicle; two transformers on the vehicle, each having a primary winding energized from said source and each having a secondary winding 7 the potential of which is applied across the two rails of the track by means of a pair of rail shoes, one pair for each secondary winding, for breaking down the rail film to improve shunting of the track; two low impedance connections from one to the other rail, carried by the vehicle and joined together electrically, which serve as return paths for the film breakdown currents furnished by said two secondary windings respectively, a current limiting reactor for each of said two transformers for limiting the magnitude of the film breakdown current supplied from said transformers, and a mid-tap reactor connected between the primary windings of said two transformers in such manner that currents from said source flow through the mid-tap to the respective primary windings in opposite directions in the two sections of said mid-tap reactor.

6. In combination, two adjoining sections of railway track each provided with an alternating current track circuit, a circuit for applying rail film breakdown current across the two rails of said track at a pair of separated locations along the track, and a reactor having an intermediate tap and connected into said circuit in such manner that the breakdown currents will flow in the two portions of said reactor in opposing directions thereby tending to neutralize the reactor impedance in the film breakdown path and at the same time maintaining a substantial impedance in the energy transfer path to minimize feed-over from one to the other rail section at such times as said current-applying circuit bridges the rail joints between said sections.

CHARLES R. BEALL. 

